Access closure for an air inflated structure

ABSTRACT

An access closure for an air inflated structure consisting briefly of a platform, a relatively impervious chamber having a rotatable wall formed with an access opening, and optional means for pre-pressurizing the chamber to maintain a relatively constant air pressure within the inflated structure during movement of persons and material in and out of the structure.

United States Patent [191 Duquette Aug. 13, 1974 ACCESS CLOSURE FOR AN AIR INFLATED STRUCTURE [76] Inventor: William L. Duquette, 6170 Thornton Ave., Newark, Calif.

[22] Filed: Dec. 14, 1972 [21] Appl. No.: 315,152

[52] US. Cl 52/2, 49/41, 135/14 D [51] Int. Cl. E04b l/34, E04g 11/04 [58] Field of Search 52/2; 49/40, '41, 68;

61/69 R; 14/71; 128/1 R; 135/14 D [56] References Cited UNITED STATES PATENTS 2,516,419 7/1950 Reyniers 128/1 R 3,314,198 4/1967 Frisk 52/2 Lloyd 61/69 R 3,478,472 11/1969 Kwake 52/2 3,561,174 2/1971 Schneidler 52/2 FOREIGN PATENTS OR APPLICATIONS 1,089,960 10/1954 France 49/40 875,101 '6/1942 France 49/41 Primary Examiner-l-lenry C. Sutherland Attorney, Agent, or Firm-James R. Cypher [57] ABSTRACT An access closure for an air inflated structure consisting briefly of a platform, a relatively impervious chamber having a rotatable wall formed with an access opening, and optional means for pre-pressurizing the chamber to maintain a relatively constant air pressure within the inflated'structure during movement of persons and material in and out ofthe structure.

2 Claims, 11 Drawing Figures PAIENIE AUG 1 31974 SHfU 2 BF 4 FIG. 7

PAIENIED nus 1 31924 SHEEN-M4 FIG; IO

FIG.

FIG. 9

ACCESS CLOSURE FOR AN AIR INFLATED STRUCTURE BACKGROUND OF THE INVENTION Conventional rigid structures do not require door systems capable of maintaining pressure differences between the inside of the building and the outside atmospheric pressure.

Since World War II, a new type of enclosure has come into use known as an air supported structure. An air supported structure is defined as any building constructed of high strength fabric or film (or any combination thereof) which achieves its structural shape, stability, and support by pretensioning with internal air pressure. The structure is sometimes referred to as an envelope which is a lightweight,pretensioned shell, usually constructed from a durable coated fabric such as nylon. No rigid columns or frames are required and thus an air structure is an integral system of mutually operating components wherein each element is designed for optimum efficiency to provide reliable performance.

While the design of the envelope itself has reached a highly sophisticated degree in the state of the art, the

design of the access openings has not. Instead of designing an access opening which cooperates with the dynamics of the envelope, present designers have borrowed heavily from standard access openings used in rigid non-pressurized structures. Thus, in presently existing air structures, one sees the standard revolving double leaf x shaped door or the common vestibule and double system of doors. Both the double leaf revolving door and the vestibule are well suited to the loss of heat in cool climates or heat gain in air conditioned buildings but they do not meet the problem of a structure which depends upon the maintenance of a constant pressure for its structural integrity.

Without a constantly maintained pressure, the envelope is subjected to a flexing-each time a person enters Another objective is to maintain normal operating pressures within the structure, expecially during high the building through the standard double leaf revolving door or the double access doors. The number of flexcycles increases the likelihood of fatigue failure in the envelope and particularly at the anchorage points.

BRIEF SUMMARY OF THE INVENTION The gist of the present invention is the use of a specially designed access opening structure and system which maintains anearly constant pressure within the envelope of an air supported structure during entry and exit of persons from the structure.

An object of the present invention is the use of an access opening structure and system which provides a chamber which is temporarily sealed off from the outside atmospheric pressure and the inside elevated pressure of the air supported structure and automatically prevents any continous major loss of air pressure through the access opening.

Another objective of the present invention is to prevent early fatigue failure of the envelope due to flexing especially at the anchorages caused by temporary sudden drops in the air pressure when a door is opened and the concomitant high pressure when the blower system is turned on to bring the pressure-up to'and slightly over normal envelope pressure by pre-pressurizing the unique entrance chamber.

external winds when stresses and deformation of the envelope are greatest.

A still further objective is to minimize on/off operation of backup blowers in order to save the life of the motors.

Still another object is to provide an access closure for an air supported structure which is simple and reliable to operate, has few moving parts and is relatively inexpensive to manufacture.

Since most of us are psychologically conditioned to rigid structures, and building movement is associated with earthquake, hurricanes and possible building collapse, it is an object of this invention to maintain a nearly constant pressure within the structure so that there is little or no detectable movement of the envelope.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross sectional view of the access closure and a portion of an air supported structure constructed in accordance with the present invention, and taken substantially along line l1 of FIG. 2.

FIG. 2 is a plan view of the access closure and a portion of an air supported structure shown in FIG. 1.

FIG. 3 is a plan view of a portion of the structure shown in FIG. 2 showing the closure in a different mode of operation.

FIG. 4 is a cross section of the invention with portions cut away for purposes of illustration.

FIG. 5 is a cross sectional view of another form of the invention taken substantially along the line 5-5 in FIG. 6.

FIG. 6 is a plan view of the form of the invention shown in FIG. 5.

FIG. 7 is a cross sectional view taken along line 7-7 of FIG. 5.

FIG. 8 is a schematic diagram of still another modified form of the invention.

FIG. 9 is a plan view of another form of the invention.

FIG. 10 is an elevational cross section of the invention taken along line l0l0 of FIG. 9.

FIG. 11 is a cross section taken along line 11 of FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The pressure differential in an air supported structure is so slight as not to be perceptible to anyone entering or leaving, but the life and efficiency of the mechanical support system and the psychological acceptance of the structure requires that the pressure level be maintained within a constant specified operational range. Inflation pressures of 1 inch water column differential is normal and envelopes are generally designed for 1.5 inch water pressure to withstand design wind loads of mph.

The access closure of the present invention for an air supported structure consists briefly of a platform 3 adapted for receivingpeople and objects spanning the lower part of the opening in the'air supported structure; an air impervious rotatable wall 4 enclosing the platform and mounted for rotation relative to the platform and forming a comparatively air tight seal therewith, the wall having an opening 6 therein adapted for receiving persons and objects entering the structure and having a first position in registration with the outside of the structure as shown in FIG. 2, a second position, as shown in FIG. 3 in registration with the means described below, and a third position in registration with the inside of the structure; means in conjunction with the wall and the platform forming a comparatively air tight chamber; a frame adapted for sealing engagement with the opening in the air inflated structure and being in sealing sliding engagement with the platform and the rotating wall; and means for elevating the pressure in the chamber when the rotating wall is in the second position and for sustaining the elevated pressure until the opening reaches the third position.

it should be noted at the very outset of the description that the access closure of the present invention differs radically from the standard revolving door. The standard revolving door is divided into four chambers by four panels which intersect and rotate about an axis at the cross sectional center of the door. The present invention has no panels inside the opening and thus the person entering the enclosure enters into a relatively spacious opening. Further, in the standard revolving door, the curved walls are stationary. Quite the opposite is true of the present invention where the wall 4 is movable.

Wall 4 is here shown as generally cylindrical in shape and this appears to be the preferred form, but it should be noted that this invention is not limited to a cylindrical wall. The chamber could be a polysided wall, with only the frame being required to seal the perimeter as it is rotated. For purposes of illustration, the wall 4 will hereafter be described as cylindrical.

Wall 4 is mounted for rotation about a vertical axis. Rotation may be accomplished in various ways. As shown in FIG. 1, a ceiling 7 is attached to the top of wall 4 and is journaled by bearing 8 to stub shaft 9 affixed to member 11 of the frame. The bottom of the wall 4 is supported by caster wheels 12 which roll on a circular track 13. Thrust rollers 14 may be mounted on the floor base 16 and entrance base 17 to engage the lower edge of wall 4 to keep the wall on its vertical axis.

Various means may be used for forming the relatively air tight chamber. Various flexible sealing means may be used and are omitted in the drawings for purposes of brevity. Actually, the chamber should never be entirely air tight as this could result in a hazardous situation should the rotating wall become jammed and further, it is not necessary to have a completely air tight entrance as the structure itself is designed for the flow of air to the atmosphere to maintain fresh air within the structure.

The frame for holding the rotating portion may be constructed in various ways and a second preferred way will be described later. As shown in FIGS. 2, 3, and 4, the frame consists of an outer wall 18 which may be formed with an air inlet opening 19 where fresh air enters in the direction shown by arrow 21. A side wall 22 separates the access closure from the inside of the air structure as well as the outside and an inner wall 23 joins the side wall 22 and is placed inside the air structure. A curved wall 24 joins the inner and outer walls and is formed for smooth sealed and sliding relation with cylinder wall 4. The means for elevating the pressure within the chamber consists of a blower fan 26 which is of a size selected to meet the design requirements dictated by the size of the chamber, the size of the envelope and the pressure requirements of the envelope. For example, a fan delivering 900 c.f.m. is adequate for a structure having about 27,000 cubic feet.

, ln order that on/off operation of the blower 26 is not necessary each time a person wishes to enter or leave the structure, a vent passage 27 is provided in the frame which leads to two discharge ports. The first port may consist ofa plurality of openings 28 in wall 24 so as to dissipate the energy of the air in order that persons moving through the chamber will not be bothered by any air velocity. It is this port which pre-pressurizcs the chamber to a pressure approximately equal to the inside pressure of the envelope. The second port is shown at 29 which enters directly to the inside of the air supported structure. Preferably this port is provided with a check valve 31 so that no air will escape from the air supported structure to the passage 27 and thence through openings 28 during pressurization of the chamber. Because of the pressure difference, valve 31 tends to close as soon as the opening 6 is in registration with the port openings 28.

Operation of the access closure of the present invention is as follows. When a person enters the entry way 32 between walls 33 and 34, he passes through opening 6 and stands upon platform 3. He then grasps handle 36 and moves the cylindrical time. 4 in the direction shown by arrows 37. As the entry way is closed, opening 6 opens to discharge openings 28 and fresh, pressurized air moves through the frame as shown by arrows 38 through blower 26, up through passage 27 to pre-pressure chamber 27a and into the chamber surrounded by wall 4 which is now sealed from both the outside atmosphere and the inside of the air supported structure. Check valve 31 is normally closed at this point in the procedure. As the wall 4 is rotated, opening 6 comes in registration with the inside entry way to the envelope. Since the pressure of the chamber is equal to the pressure of the envelope, no drop in air pressure in the structure occurs.

FIGS. 5, 6 and 7 show an access closure which is essentially the same as the previously described closure except that the design is more suitable for larger structures where it is often necessary to permit entry or egress of several persons at one tiem.

The access closure consists briefly of a cylindrical wall 41 resting on casters 42 and journaled for rotation about vertical axis 43 by bearing 44 rotatably connected to frame 46. Side thruster rollers 47 maintain the bottom of the cylinder in vertical alignment. Suitable light fixtures 48 are provided in the upper wall 49 or the rotating cylinder. A stationary platform 51 is formed in close sealing fit with the bottom portion of the wall 41. Wall 41 is provided with an opening 52 through which persons enter the access chamber.

A frame carrying the air pressurizing blower is located in one portion of the frame. This frame may consist of an outer wall 53, a side wall 54, an inner wall 56 and a curved wall 57 formed concentrically and in close fit with curved wall 41. These walls form a chamber through which air flows as shown by arrows 58. Air enters from atmosphere through opening 59 and is pressurized by blower 61. The pressurized air in chamber 62a either moves through openings 62 as shown by arrow 63 and into the chamber surrounded by wall 41 or it enters the air supported envelope 64 as shown by arrow 66 through opening 67.

At the other side, curved wall 68 is formed in sealed, coaxial, sliding fit with wall 41. A chamber may be formed by outside wall 69, side wall 71'and inside wall 72.

Instead of a manual operation, the wall 41 may be operatively connected to a remote control switch for operating the wall by powered means. One example of a way of operating the wall is shown in FIG. 7. An electric motor 73 moves belt 74 which is wound about the cylindrical wall 41.

Operation of the access closure is nearly identical to the previously described system. Persons enter opening 52 step onto the platform 51 and the button is pushed to activate motor 73. When opening 52 reaches discharge openings 62a, the access between walls 69 and 53 will be closed by wall 41 and the pressurized air from chamber 62 enters the chamber formed by wall 41 and the curved wall 57. As the opening 52 reaches the access opening between walls 56 and 72, the pressure within the chamber formed by wall 41 will be substantially equal to the pressure within the envelope 64.

It is possible that the wall 4 which is mounted to rotate about its vertical axis could be rotated about a horizontal axis but for most relatively small structures the vertically rotatable wall seems preferable.

It has been found that where the operating pressure of the air supported structure is maintained at less than three inches of water pressure or where slight intermittent drops in air pressure are not so critical to the life of the structure, the type of closure described need not be pre-pressurized each time the closure is rotated.

In this modified form of the invention where the structure is maintained at less than 3 inches of water pressure the pre-pressured chamber described is dispensed with and the closure on both sides is identical to the closure shown in FIG. 6 consisting of walls 68, 69, 71 and 72. Thus, the invention briefly consists of a relatively air impervious walled chamber such as the chamber formed by wall 41 and ceiling 49, mounted for rotation about an axis having an opening 52 for selective communication with the outside of the structure at a first position. In the third position the opening 52 is in communication with the inside of the structure and at the second position, the opening is out of communication with both the inside and the outside. The alternate structure further consists of a frame having an air impervious wall such as wall 68 which forms a relatively impervious seal with the opening 52 when the wall is being rotated from the first to the third position to prevent direct pressure communication between the inside and outside of the structure.

The previously described forms of the invention which are shown in the drawings set forth a closure in which the cylinder 4 is of impervious material greater than 270 in circumference. Generally it is desirable to operate the door by rotating it 360 and in the same direction. A modified form of the invention is shown in FIG. 8 in which the wall 4' operates reciprocally and does not turn a full 360.In this form of the invention, the non-rotatable cylinder 24' has a chamber wall is impervious 360 and merely has a first opening 6' in the wall creating an outside entry communicating with the outside of the structure and a second opening 6" creating an inside entry communicating with the inside of the structure. The door closing member 4 has a large personnel opening 106' is mounted for rotational movement about a vertical axis and has a first position closing the secondopening 6" and exposing the first opening 6', a second position closing both of the openings and a third position closing the first opening and exposing the second opening.

This form of the invention may also be provided with means for elevating the pressure of the chamber to approximately the air pressure of the inside of the structure during movement of the door closing member from the first position to the second position by providing a pre-pressure chamber 27a between openings 6 and 6" with openings 28 in wall 28".

FIGS. 9, 10 and 11 show still another form of the invention in which the access closure is not prepressurized but is motorized.

Briefly, the invention consists of a relatively air impervious walled chamber 81 mounted for rotation about an axis 82 having an opening 83 for selective communication with the outside 84 of an air inflated structure at a first position as shown in FIGS. 9 and 10, with the inside 86 of the structure at a third position, and being out of communication with both the inside and outside at a second position. The invention also includes a frame having an air impervious wall in communication with the opening in the rotating chamber at the second position of the chamber and forming a relatively air impervious seal with the wall of the chamber during rotation of the chamber between its first and third positions to prevent direct pressure communication between the inside and outside of the structure. In the form of the invention shown in FIGS. 9, 10 and 11, the frame consists of walls 87 and 88 which support ceiling 89. Metal flanges 91, 92, 93 and 94 jut out from each corner and are in turn fastened to metal vertical walls 95 and 96 which are curved to fit closely with the walls of the rotating chamber.

As stated above, the walled chamber is formed in the shape of a cylinder mounted for rotation about a vertical axis and has circular vertical walls, a ceiling 97 and the bottom portions of the walls 98 are in sliding sealing engagement with an impervious floor area.

Preferably a platform 99 is constructed for receiving people and objects spanning the lower part of the opening. As shown in FIG. 10, the lower part of the rotatable wall carries an inturned flange 101. Although the seal between the platform and the flange 101 need not be air tight, it should be relatively close fitting to permit gross air loss.

The closure may be manual or motorized depending upon the size and usage of the closure. As shown in FIG. 10, the motorized version may have a motor 102 mounted above the chamber. The closure is supported by a hanger 103 resting on a hanger bearing 104 which in turn rests on a hanger support 106. The shaft 107 is connected to the ceiling 97 of the rotating chamber. A circular drum 108 is mounted on the ceiling of the chamber and a belt 109 is wrapped about the drum and about a pulley 110 on the motor shaft 111.

Vertical alignment of the rotating chamber can be effected by mounting a plurality of rubber tired dolly wheels 112 on vertical shafts 113 about the outside of the rotating wall 81. Rotation of the chamber is shown by arrows 114.

As shown in FIG. 10, the entire revolving member is light enough so that it may be supported from above on bearings 104 and no support from the floor is necessary.

I claim:

1. An air supported structure having an access opening therein and an access closure and pressurizing means within said access opening, said closure and pressurizing means comprising:

a. a rotatable cylinder positioned in said access opening of said air structure and mounted for rotation about a vertical axis, said cylinder being formed with a vertical side wall having a large personnel opening therein and a ceiling;

b. a non-rotating floor area position in underlying relation to said cylinder and forming a relatively air tight sliding seal with the bottom of said vertical cylinder wall;

0. a frame having a plurality of walls forming a chamber and one of said walls including a vertical arcuate wall positioned in close fitting relation with said rotatable cylinder preventing substantially all air loss therebetween and a portion of said arcuate wall being formed with a plurality of air openings positioned for selective communication with the inside of said cylinder through said personnel openmg;

d. said chamber wall being formed with an air inlet port communicating with the atmosphere and an air discharge port communicating with the inside of said air inflated structure;

e. blower means communicating with said air inlet port for elevating the air pressure within said chamber to approximately the air pressure inside said air inflated structure, and for supplying air to said air inflated structure through said discharge port;

f. a check valve mounted in said discharge port insuring one way passage of air to said air inflated structure;

g. said large personnel opening in said cylinder and said vertical arcuate wall in said frame being dimensioned so that upon rotation of said cylinder to a first position said large personnel opening is in communication only with the outside of said structure, upon rotation of said cylinder to a second position said personnel opening is in communication with said air openings in said arcuate wall of said frame for receiving air from said blower means for pressurizing the inside of said cylinder and said personnel opening is out of communication with both the inside and outside of said air inflated structure, and upon rotation of said cylinder to a third position said personnel opening is in communication with the inside only of said air inflated structure; and

h. said rotatable cylinder wall normally being in close fitting engagement with said air openings in said arcuate wall of said frame so as to prevent air flow through said openings when said rotatable cylinder is in said first position.

2. An air supported structure having an access opening therein and an access closure and pressurizing means within said access opening, said closure and pressurizing means comprising:

a. a non-rotatable cylinder having a floor, arcuate vertical wall and a ceiling positioned in said access opening of said air structure and said cylinder being formed with an outside entryway in said vertical wall communicating with the outside of said air inflated structure and an inside entryway in said vertical wall spaced from said outside entryway communicating with the inside of said air inflated structure;

b. an arcuate door closing member mounted for rotational movement about a vertical axis within the vertical wall of said non-rotatable cylinder in close fitting relation thereto, said door closing member having a large personnel opening therein and said door closing member having a first position wherein said opening in said door closing member is in communication with said outside entry way of said cylinder and said door closing member closes said inside entryway, said door closing member having a second position wherein said opening in said door closing member is out of communication with both said inside and outside entryways of said cylinder and said door closing member closes both said inside and outside entryways, said door closing member having a third position wherein said opening in said doorclosing member is in communication with said inside entryway;

c. a frame having a plurality of walls forming a chamber and one of said walls including a vertical arcuate wall positioned between the outside entryway and said inside entryway of said cylinder and forming a close fitting relation with said arcuate door closing member, and a portion of said arcuate wall being formed with a plurality of air openings positioned for selective communication with the inside of said non-rotatable cylinder through said opening in said door closing member when said door closing member is in said second position;

d. said chamber walls being formed with an air inlet port communicating with the atmosphere and an air discharge port communicating with the inside with said air inflated structure;

e. blower means communicating with said air inlet port for elevating the air pressure within said chamber to approximately the air pressure inside said air inflated structure, and for supplying air to said air inflated structure through said discharge port;

f. a check valve mounted in said discharge port insuring one way passage of air to said air inflated structure;

g. said blower means elevating the pressure inside said non-rotatable cylinder through said air openings in said arcuate wall of said chamber when said door closing member is in said second position; and

h. said door closing member being mounted so as to prevent air flow through said openings in said vertical arcuate wall of said frame when said door closing member is in said first position. 

1. An air supported structure having an access opening therein and an access closure and pressurizing means within said access opening, said closure and pressurizing means comprising: a. a rotatable cylinder positioned in said access opening of said air structure and mounted for rotation about a vertical axis, said cylinder being formed with a vertical side wall having a large personnel opening therein and a ceiling; b. a non-rotating floor area position in underlying relation to said cylinder and forming a relatively air tight sliding seal with the bottom of said vertical cylinder wall; c. a frame having a plurality of walls forming a chamber and one of said walls including a vertical arcuate wall positioned in close fitting relation with said rotatable cylinder preventing substantially all air loss therebetween and a portion of said arcuate wall being formed with a plurality of air openings positioned for selective communication with the inside of said cylinder through said personnel opening; d. said chamber wall being formed with an air inlet port communicating with the atmosphere and an air discharge port communicating with the inside of said air inflated structure; e. blower means communicating with said air inlet port for elevating the air pressure within said chamber to approximately the air pressure inside said air inflated structure, and for supplying air to said air inflated structure through said discharge port; f. a check valve mounted in said discharge port insuring one way passage of air to said air inflated structure; g. said large personnel opening in said cylinder and said vertical arcuate wall in said frame being dimensioned so that upon rotation of said cylinder to a first position said large personnel opening is in communication only with the outside of said structure, upon rotation of said cylinder to a second position said personnel opening is in communication with said air openings in said arcuate wall of said frame for receiving air from said blower means for pressurizing the inside of said cylinder and said personnel opening is out of communication with both the inside and outside of said air inflated structure, and upon rotation of said cylinder to a third position said personnel opening is in communication with the inside only of said air inflated structure; and h. said rotatable cylinder wall normally being in close fitting engagement with said air openings in said arcuate wall of said frame so as to prevent air flow through said openings when said rotatable cylinder is in said first position.
 2. An air supported structure having an access opening therein and an access closure and pressurizing means within said access opening, said closure and pressurizing means comprising: a. a non-rotatable cylinder having a floor, arcuaTe vertical wall and a ceiling positioned in said access opening of said air structure and said cylinder being formed with an outside entryway in said vertical wall communicating with the outside of said air inflated structure and an inside entryway in said vertical wall spaced from said outside entryway communicating with the inside of said air inflated structure; b. an arcuate door closing member mounted for rotational movement about a vertical axis within the vertical wall of said non-rotatable cylinder in close fitting relation thereto, said door closing member having a large personnel opening therein and said door closing member having a first position wherein said opening in said door closing member is in communication with said outside entry way of said cylinder and said door closing member closes said inside entryway, said door closing member having a second position wherein said opening in said door closing member is out of communication with both said inside and outside entryways of said cylinder and said door closing member closes both said inside and outside entryways, said door closing member having a third position wherein said opening in said door closing member is in communication with said inside entryway; c. a frame having a plurality of walls forming a chamber and one of said walls including a vertical arcuate wall positioned between the outside entryway and said inside entryway of said cylinder and forming a close fitting relation with said arcuate door closing member, and a portion of said arcuate wall being formed with a plurality of air openings positioned for selective communication with the inside of said non-rotatable cylinder through said opening in said door closing member when said door closing member is in said second position; d. said chamber walls being formed with an air inlet port communicating with the atmosphere and an air discharge port communicating with the inside with said air inflated structure; e. blower means communicating with said air inlet port for elevating the air pressure within said chamber to approximately the air pressure inside said air inflated structure, and for supplying air to said air inflated structure through said discharge port; f. a check valve mounted in said discharge port insuring one way passage of air to said air inflated structure; g. said blower means elevating the pressure inside said non-rotatable cylinder through said air openings in said arcuate wall of said chamber when said door closing member is in said second position; and h. said door closing member being mounted so as to prevent air flow through said openings in said vertical arcuate wall of said frame when said door closing member is in said first position. 